Long-term objectives of this laboratory are: (1) to understand the mechanisms underlying altered functional (metabolic) organization in the central nervous system (CNS) produced by peripheral denervation or sensory disuse; (2) to determine anatomical and physiological factors that enhance or retard altered CNS organization and recovery of function; (3) to determine the behavioral consequences of altered CNS organization; (4) to apply this knowledge to the investigation of the functional plasticity recovery of function relationship in humans possessing lesion produced somesthetic deficits. Human studies would involve the use of the (llC) - 2DC position emission tomography technique. Results to date indicate a dynamic functional reorganization of the trigeminal afferent pathway and SI cortex following partial peripheral denervation. The extent of reorganization is, however, variable. The specific aims of our continued effort will identify factors which contribute to this variability: (1) to examine the effects of CNS maturation on the functional alterations at subcortical levels of the rat vibrissa-first somatosensory (SI) cortex system; (2) to determine the effects of chronic intervention on the functional alterations of the spared C3 (SC3) representation in the vibrissa pathway; (3) to determine the behavioral consequences of the SC3 metabolic alterations; (4) to determine the status of SC3 innervation to determine the CNS effects of variations in the peripheral innervation pattern and (5) to determine the influence of fiber competition associated with trigeminal and non-trigeminal related fiber systems on the altered SC3 functional representation in the vibrissa pathway. The precisely organized rat facial vibrissa-SI "barrel" system will be used to study denervation produced altered metabolic organization centrally. The altered functional representation of facial vibrissa C3, which is spared (SC3) following denervation of remaining vibrissae, will be examined at all levels of the vibrissa-SI cortex pathway of neonatal and adult rats under different experimental conditions using the quantitative (14C)-2 deoxyglucose technique. Behavioral consequences associated with the altered SC3 metabolic representation in the vibrissal pathway, will be examined using species-specific locomotor response tests.